Automatic furnace control



Aug. 19, 1930, J. A, DORAN AUTOMATIC FURNACE CONTROL 6 Sheets-Sheet Filed Aug. 12, 1926.

'Aug. 19, 1930. J, DORAN 1,773,705

AUTOMATIC FURNACE CONTROL Filed Aug. 1-2, 1926 s Sheets-Sheet 5 Aug. 19, 1930. I J.- A'. DORAN ,J -1 ,773,70 5

7 AUTQMAT I C FURNACE CONTROL Filed Aug 12, 192 v 6 Shets-Shet 4 Jamey Zara)? Aug. 19, 1930! J. A. 130mm AUTOMATIC FURNACE CONTROL Filed Aug. 12, 1926 6 Sheets-Sheet war/e1 Au .-19,1930. D RA 1, 773, 7o5

AUTOMATIC FURNACE CONTROL Fi led Aug. '12. 1926 6 Sheets-Sheet 6 Q 7 amas 4 Jam;

' (QJWQ Q Patented Au 19, 1930 firms A. now, or rnovmmrca, nnonn rsnnm AUTOMA TIC FURNACE CONTROL Application filed August 12, 1920. Serial in. 188,798.

My invention relates to furnaces, and comprises an improved method of re ulatmg the air supply, and also if desired, t e fuel supply thereto. Though other types of fuel may be employed, my invention is particularly adapted for an oil burning steam boiler furnace.

Whereas man attempts have been made to control the fue su ply to a furnace, very little attention has een paid heretofore to the air supply thereto. While the fuel supply has been regulated in various manners, particularly by means of the boiler pressure, it seems to have been overlooked that for eflicient combustion, economy of fuel, etc., the air supplied should also be accurately adjusted to give the correct amount of oxygen to the furnace for most efiicient combustion. It has been recognized that the flue gases give an indication of the supply of oxygen to the furnace. If the supply of oxygen is too great, the excess cold air coming through the furnace will cause inefliciency, excessive flue temperature, low CO and an excessive amount of oxygen. If on the other hand the supply of oxygen is insufficient, there will be inefiiciency, reflecting in low flue temperature GO. and low CO in the flue gases and excessive smoking. If however, the supply of oxygen can be correctly regulated, an exact amount of oxygen will be delivered to the furnace to exactly'consume all the carbon present in the fuel, thus securing the most perfect combustion possible. I am aware that attempts have been made to control the air supply through various types of CO analyzers. These devices however, are complicated, expensive and have not to date, so far as I am aware reached the stage of perfection where they may be considered practicable. I have discovered that a certain tem-' perature necessary for most eflicient combustion exists, i. e., which will produce the highest percentage of CO in the flue gases, WhlCh may bereadily ascertained; and that if the temperature falls below this most eflicient or selected temperature, it will be an indication of an insuflicient amount of oxygen; whereas, if the temperature rises above this selected temperature, it will be an indication of too much air, with consequent loss of efliciency of combustion.

The main object of my invention is to automatically regulate the air suply to a furnace through the medium of the temperature .55 of the flue gases to maintain a flue temperature indicative of the correct supply of oxygen for'm'ost efiicient combustion under varymg conditions.

As stated, it is also desirable to regulate no the fuel supply in accordance. with the demand on the furnace and my invention further comprises the combination of means to automatically regulate the fuel supply to the furnace, and means including a thermo re-te sponsive element in the flue acted upon by the flue gases to automatically controlthe air supply to said furnace in order to deliver the correct amount of oxygen to said furnace to secure most efiicient combustion. v0

As stated my preferred embodiment is a steam boiler furnace, and I preferably automatically regulate the fuel supply to said furnace through the medium of the boiler pressure, directly or indirectly, and I pro- '75 vide, in combination with said means controlled by the boiler pressure to automatically regulate the fuel supply to the furnace to maintain a constant boiler pressure, means including any type of element in the flue-act- '80 ed upon by the flue gases to automatically control the air supply to said furnace to deliver the correct amount of oxygen to said furnace to secure most eficient combustion. My invention also includes, I believe for the first time, the combination of means controlled by the boiler pressure to automatically regulate the fuel supply and means controlled by an element in'the flue, acted upon by the flue gases to automatically control the air '90 supply, both of which means combine with each other to produce the new result of almostperfect combustion. I have found that the flue temperature reflects and substantially corresponds with the CO content over a considerable range or load; but that this relation diflers somewhat when the boiler is below or above its economical capacity; particularly when'the'boiler is overloaded, the velocity of the burning gases must be greater, and the -nace, or both conjointly.

ulation of air to o erate over all ranges of load than can possi ly occur.

The air regulation may be effected 1n any suitable manner, either by means of dampers in the flue or by means of the front dra t or louvre control normally located in the fur- As the result of automatically adjusting the air supply as indicated above I obtain a more perfect combustion in the furnace than hitherto thought possible; by delivering the correct amount of oxygen to the furnace, .the

' carbon in the fuel is substantially completely consumed, thereby decreasing the amount of objectionable soot hitherto practically always formed in the boiler tubes and in the flue; thus reducing the cost of cleaning the boiler tubes and flue, and lengthening their life. A further result of my invention is to practically eliminate the smoke nulsance, which raises such havoc in'our larger c1t1es and which city governments have hitherto attempted to control. I

.'A further object of my invention is to lessen in an appreciable degree the amount of fuel necessary for perfect combustion, for the correct amount 0 oxygen is always delivered to the furnace in order that all combustible matter in the fuel will be substantially consumed.

In my preferred embodiment which is specifically adapted for an oil burning furnace, I preferably control the fuel supply through the medium of the boiler pressure in a wellknown manner and I preferably provide an electric controlling device including a 3- phasecircuit and a series of relay switches to'actu'ate motive means to open or close the louvre and/or damper. It is obvious that it is only necessary to move the louvre and/or damper a slight amount to compensate for slight changes in atmospheric conditions, and it is necessary to provide a train of reducing gearing to secure a slow movement of the louvre from an ordinary high speed motor. A further object of my invention in my specific embodiment is to provide means to compensate for the time required for the gases to passthrough the boiler to the flue and the usual lag in the action of a thermo-responsive element, in my preferred embodiment said means comprising an intermittent gear.

In starting a furnace it is desirable to vary the amount of air and I therefore provide the combination with said automatic means heretofore described independent manuallyoperated means for regulating the louvre and/or damper to vary the air supply.

- My invention is preferably provided with means preferably controlled by the boiler overload to cooperate with the usual air control means to vary the air supply specifically the selected temperature with changes in load on the boiler. I also provide in addi-' tion to the automatic temperature selector means just referred to, manually operated means to adjust the selected temperature. It is obvious however, thatv the automatic means to select the proper temperature for variations in load may be dispensed with and that I may employ the manually controlled means to select the temperature at a point just above that at which smoking occurs.

As is apparent my invention includes not only the actual means or apparatus heretofore described for controlling the fuel and air supply, but also the method of so doing heretofore described. j

These and such other objects of my invention as may hereinafter appear will be best understood from a description of various embodiments thereof such as are shown in the accompanying drawings.

In the drawings Fig. l is a front elevation of a steam boiler oil burning furnace having my invention attached andemploying an indicating thermometer in the flue, my preferred type of thermo-responsive element.

Fig. 2 is a diagrammatic view of part of .the preferred embodiment of my invention illustrating the indicating thermometer, the contact'forming device,'the primary and power luu electric circuits, the motor, the diaphragm valve acted upon by the boiler pressure, and the means controlled by said valve to move the automatic selector of said contact form ing device. I

Fig. 3 is a cross sectional view of the louvre and burner proper of the preferred type of oil burning apparatus I employ. I

Fig. 4 is a front elevation of the motor, the gear box, the louvre and drive from the motor to the louvre.

Fig. 5 is a plan view of the motor and the drive including the gear box having its cover removed to show the reducing train of gearin therein.

Fig. 6 is a sectional line 6-6 of Fig. 5.

Fig. 7 is a sectional View taken along the line 7-7 of Fig. 5.

Fig. 8 is a diagrammatic view of a portion of the apparatus shown in Fig. 2, Where the thermoresponsive means comprises a thermostat mounted in the flue and the contact forming device is that preferab y employed when a thermostat is used.

Fig. 9 is a sectional view'taken along the line 9-9 of Fig. 8.

view taken along the IUD IHI

hill

awavoe Fig. 10 is a sectional view taken along the line 10-10 of Fig. 8.

Fig. 11 is a diagrammatic view illustrat ng my invention in use in a domestic heating .furnace, the oil supply being controlled by a suitable thermostat and the air an ply by a suitable thermostat in the flue w ch actuates a hydraulic motor to move the louvr and damper.

Fig. 12 is a diagrammatic view of my 1nvention employed on a as burning furnace having a thermostatin t e oven for controlling the gas supply and a thermostat m the tips for automatically adjusting the air sup- P ln the drawings, wherein like characters of reference indicate like parts throughout,

20 generally indicates a furnace, in m preferred embodiment as illustrated in. ig. 1, comprising a usual steam boiler furnace 20 having a boiler 22 and a burner 24. Though as stated any type of fuel, solid,liquid, or gaseous may be employed, 1n my preferred embodiment, I pre era'bly emplo themechanical oil burner 24, which as s own 1s of a type which at present is largely used in 1ndustrial plants and includes the adjustable .louvre 26 foradjusting the air supply thereto and the burner proper 28. Thefurnace 20 isprovided witht eusual flue 30 for the prodnets of combustion. Said flue 30 is preferably provided with the usual damper 32 suitably mounted therein.

s stated, my invention primarily consists in the new method I employ, of automatically regulating the air supply to a furnace through the medium of the temperature of the flue gases alone to maintain a flue temperature indicative of the correct amountof oxygen for most eficient combustion. To this end I provide the thermo-responsive ele ment 34 in the flue. Though any suitable type of thermo-responsive element such as the thermometer s own in Figs. 1'?, the thermostat shown in Figs. 8-10, a pyrometer or other type may be employed, in my preferred embodiment, I employ the thermometer 34. Said thermometer 34 is provided with the usual means or indicating material responsive to variations in the temperature of the flue. As hitherto explained, the air supply to the furnace is regulated through the medium of the louvre or other draft devices 26 located below the combustion area i in the furnace. I provide means whereby the able drive 38 actuates the louvre 24 and/or damper 32 in the desired direction and I also provide suitable electrical connections controlled by said thermo-responsive element 34 to actuate said motive means 36 in either direction. Though the motive means 36 may comprise a reversible motor 36 as shown in my preferred embodiment it may comprise the hydraulic motor 36' shown in Fig. 11 or if desired may comprise two motors, each to move the louvre and/or damper in eitherdirection.

I will now describe in detail the preferred form of electrical controlling means for said motive means 36, which I employ. I employ a suitable power circuit 39 .for this purpose. In my preferred embodiment as more particularly shown in Fig. 2, said power circuit 39 comprises the 3-phase alternating current circuit in the wires 40, 42 and 44 connected to the reversible motor 36 in such manner that the wires 42 and 44 are exchangeable in order to secure motor operation in either direc tion. In addition, I provide a primary electric circuit 48 containing the usual Wires 50 and 52 to actuate the solenoid relay switches 56 and 54 to connect the 3- phase circuit 38 to the motor 36 to drive it in either direction. 1 preferably provide two solenoid relay switches, one 56 connected to the power circuit 39 and said primary circuit 48 operative when closed by said primary circuit 48 to close the power circuit 39 by connecting the wire 42 to the terminal 42, the wire 40 to the terminal 40' and the wire 44 to the terminal 44' to drive the motor 36 in one direction and a second solenoid relay switch 54 connected to said power circuit 39 operative when closed by said primary circuit 48 to close said power circuit 39 by connecting the wire 42 to the terminal 44', the wire 40 to the terminal 40 and the wire 44 to the terminal 42 to drive said motor 36 in the opposite direction. Said switches each include a pair of levers 58 pivoted as at 60 and joined together by the insulating cross bars 62 normally retained in open position by the springs 64 and operative when the respective solenoid coil 66 is magnetized by the primary circuit 48 in a manner to be explained to be jointly pivoted through the intermittent attraction of the respective solenoid 66 for the arms 68 depending from said cross bars 62 until theupper ends 70 of the levers 58 there of contact the contacts 72 to complete and close the power circuit. The third wire 40 of the power unit does not pass through the solenoid switches 54 and 56 at all. The wires 42 and 44 are connected to the contact points 7 2 and the levers 58 of each respective switch 54 and 56 so that when the switch 54 is closed, as hitherto explained the motor 36 will be driven in one direction and when the solenoid switch 56 is closed as hitherto explained the motor 36 will be driven in the opposite direction.

As hitherto explained, I provide a reversible drive from said motive means 36 to said louvre 26 and damper 32 to alternately open or close them. As hitherto explained, to accord with variations in atmospheric load or other variable conditions it is necessary to turn the louvre 26 or damper 32 a very slight amount. at each intermittent movement and thus I provide a reducing train of gearing between said motive means 36 and the louvre 26'and/or damper 32. The details of said drive are'shown in Figs. 4-7. The motor shaft is preferably extended within the gear box 82 and has the worm 84 mounted thereon. Said worm 84 is adapted to enmesh the worm gear 86 mounted on the cross shaft 88 in said gear box 82 at right angles to said shaft 80. Said cross shaft 88 also has mounted thereon the worm 90 adapted to drive the worm gear 92 on the shaft 94. As explained, as a certain time is required for the gases to pass from the burner throu h the boiler to the flue and as any type 0 a thermo-responsive element is not immediately responsive, it is necessary to provide some means to compensate for said lag or combined delay and I thus for this purpose provide the train of gearing with the intermittent gears 96-98. I thus in my preferred embodiment mount the one toothed gear 96 on said shaft 94. At the opposite end of said gear box from said shaft 80 and parallel therewith is located the louvre drive shaft 97 on which is mounted the gear 98 adapted to be engaged by the one toothed gear 96 to intermittently drive said louvre drive shaft 97. The louvre. drive shaft 97 projects out of the gear box 82 and has mounted thereon above the louvre 26 the worm 100.

Fig. 3 illustrates the preferred form of oil burner 24, which I preferably employ. Said burner 24 comprises the burner proper 28, which emits the oil vapor 102 in conical form to ignite within the furnace in a conical flame. The oil for said burner is fed under pressure through the oil supply line 104, said oil supply pipe 104 being preferably provided with the hand shut off 106 located in front of the louvre door. The oil supply pipe 104 extends axially of the louvre to the burner 28. The louvre proper includes the tube 107 having the inner end 108 thereof permanently secured within the furnace wall around the burner 28, a central portion 110 flaring outwardly infunnel shape immediately exterior of said'furnace wall 112 and terminating in a cylinder portion 114 of appreciably larger diameter than the portion 108, exterior of said flaring portion 110. The cylindrical bearing portion 114 of said tube 107 is provided with a plurality of regularly spaced rectangular openings or air ports 116. The louvre also includes a cap 118 of slightly larger diameter than the diameter of the cylindrical portion 114 adapted to telescope said cylindrical portion 114 and be revolvably mounted thereon The periphery of said c lindrical cap 118 is provided w1th a plurallty of rectangular openings 120 radially disposed thereon adapted to register with said cooperating openings 116 in the cylindrical end 114. It is thus obvious that by moving the cap 118 relative to said stationary cylindrical end 114 that said respective openings 116 and 120 may be cooperatingly brought in and out of register to form a shutter device to control the amount of air supplied to said furnace20. The upper portion of said cap 118 is preferabl provided with the cooperatingly curved me 122 adapted to engage with t e threads on the worm 100. It is thus obvious that when said motive means 36 is driven in one direction a relative movement of said cap 118 on the cylindrical end 114 of said tube 107 will take place to bring said air inlet openings 116 and 120 in more complete registration to increase the sup ly of air to said furnace and that when sai motive means 36 is driven in the opposite direction a relative movement between said openings 116 and 120 will take place to lessen the composite apertures formed thereby to decrease the supply of air to said furnace 20.

Whereas any suitable type of means may be provided to open the damper 32 located in the flue 30, in my preferred embodiment I preferably employ the following: I provide the revolvable cap 118 with the depending lug 124. The damper 32 is pivoted as usual as at 126 within the flue and I preferably connect said pivoted damper with said louvre 26 by the link mechanism 128 so that when said louvre 26 is opened the damper 32 will be conjointly opened and vice versa. It is obvious that in so far as the regulation of the air supply is'concerned that the air supply may be regulated by means of the damper 32 in the flue or by the louvre damper 26 alone or both'conjointly, or in any other suitable'manner.

To provide means whereby the thermo-re sponsive element may actuate said motive means 36 in either direction, as stated, I provide the primary electrical circuit 48 and a suitable contact forming device 130 to complete said primary circuit 48 connected to said primary circuit and controlled by said thermo-responsive element 34. In my preferred embodiment said contact forming device 130 comprises an indicator of an indicating thermometer suitably modified and electrically connected, though it may take the form of the contact forming device 130 shown in Fig. 8 adapted for use when the thermo-responsive element comprises a thermostat 34. A close examination of these two contact forming devices and 130 I in the. indicator 130, said device includes a movable neutral contact member 132, which as shown in Fig. 2-comprises the indicator needle 132 of the indicator, suitably pivoted as usual at 134 to indicate the temperature on the chart 136 of said indicator. Said indicating needle 132 is controlled in the usual manner in its position by the'thermoresponsive means in the thermo-responsive element and when modified to form a contact forming device as shown is connected to the neutral wire 52 of said primary circuit. In addition, the contact forming device 130 includes a movableselector member 138 also pivoted on the pivot point 134 having two contact points 140 and 142 respectively mounted on arms of said member 138 insulated from each other, the contact 140 being connected to the primary circuit 48 through the solenoid 6 6 ofthe relay switch 56 and the other contact 142 being connected to the primary circuit 48 through the solenoid 66 of the relay switch 54. The opposite wire 50 of the primary circuit 48-from the neutral wire 52 is split and oneportion 144 is passed around the solenoid 66 of the switch 56 and is connected to the upper portion of the arm bearing the contact point 140, whereas the other port-ion 146 thereof is passed around the solenoid 66 of the relay switch 54 and connected to the arm of the selector 138 bearingthe contact point 142. The indicating needle 132 is mounted above said movable selector member 138 so that it may form a contact with the contact points 140 and 142 alternately respectively when pivoted in either direction by sweeping over the upper surface of the said contact points 140 and 142 thereby permitting the needle 132 to travel in either direction on changes in temperature without breaking the contact points 140 or 142 until the motive means 36 functions to correspondingly adjust the air supply and restore the needle 132 to a neutral position.

In the embodiment shown in Fig.8 adapted for use on a thermo-responsive element which in that case comprises a thermostat 34, the movable neutral contact member comprises the rod 132' controlled in its position by said thermostat 34' in a -manner to be explained and is connected to the neutral wire 52 of the primary circuit and the movable selector member which comprises the slidable block 138' suitably mounted in the side of the contact box 130' for vertical up and down movement therein provided with the oppositely disposed arms bearing the contact points 140 and 142' on each side of the contact point 133' of the rod 132, connected as explained to the neutral wire 52. To provide a point of contact on said rod 132 1 preferably pivotally mount the contact point 133' on said rod 132' so that it may freely pivot in one direction in a manner to be explained. The contact points 140' and 142' of said movemploy a type of .thermostat especially adapted for t is purpose and which I believe presents features of construction novel in thermostats. Instead of having the internal member 150 of the thermostat the relatively movable one, I so construct the thermostat that the outer case 152 thereof has a greater coefiicient of expansion than the internal relatively stationary member 150. For the internal member 150, I preferably employ a bar of iron or other material with a low coefficient of expansion and for the other relatively movable member I preferably employ the tube 152 of brass or other material with a relatively high coefiicient of expansion. The members 150 and 152 are permanently secured together at their inner ends within the flue by the pin 154 allowing the opposite end of the tube 152 to be free to move on the unequal expanison. The free end of said bar 150 is permanently bolted by the stud bolt 156 to a plate 158 which is firmly secured to the side of the flue wall 160. The segmental holes 162 are cutthrough the plate 158 and the sides of said tube 152 are slotted as at 164 to permit the slotted tube 152 to have a free movement through the segmental holes 162 in the plate. The outer end of said brass tube is provided with a cap 166 and contacts the short arm 168 of a lever 170 suitably pivoted as at 172. on 'a bracket 174 mounted on a box integral with the plate 158 attached to the side 160 of the flue wall,- the long arm 176 thereof being attached to the movable contact forming member or rod 132 and the long arm 176 of said lever being preferably normally forced downwards by the tension spring 178 suitably attached to the base of the box 175. It is thus obvious that on increase of heat and on expansion of said tube 152 relative to said iron bar 150 that the outer free end 166 of said tube will be forcedoutwards to force the short arm 168 of the lever outwards and thus the long arm 176 of the bell crank lever 17 0 upwards against the ten: sion of the spring 178to raise the movable contact forming member or rod 132' upwards to cause the contact point 133 thereof to contact the contact point 140 of the movable selector member 138 to complete the primary circuit 48 through the medium of the solenoid 66 of the switch 56 to cause the motive means 36 to operate'to decrease the air supply in a manner hitherto explained. It is thus 0bvious that on decrease of heat in the flue the sive expanson of said tube152 after forming contact with the contact point 140' the contact 133 may pivot away therefrom in contact therewith without mechanical injury to the automatic selector member 138' or other parts. It is not necessary to so mount 1 the contact point 133' on the movable contact forming member 132 so that it may pivot in the opposite direction for on decrease of heat in said flue the contact point 133 will merely rest against the contact point 142' of the automatic selector 138 tlretnhtgg contract ing away from the short arm ffifigssid bell crank lever 170.

..The operation of either contact forming device for either type of thermo-responsive element is thus obvious from the above description. On increase of heat in said flue said thermo-responsive element will cause said neutral contact member 132 to move to contact the contact point 140 of'the movable selector 138, to complete the primary circuit through the solenoid 66 of the relay switch, 56 to cause the relay switch in a manner hitherto explained, to operate to complete the power circuit to drive the motive means 36 to conjointly intermittently close the louvre 26 and damper 32 to lessen the air supply until the temperature, in the flue has been reduced to the selected temperature when the thermo-responsive element 34 causes said movable contact 132 to move away from said selector contact 140 to break said primary circuit 48 and thus said power circuit 39 to stop said motor and vice versa where the flue temperature falls below the desired point to move said movable contact member 132 to contact the contact point 142 of the movable selector 138 to complete the primary circuit through the solenoid 66 of the relay switch 54 to close the power circuit to operate said motive means to conjointly open said louvre and damper until the temperature of the flue has been increased to the selected temperature, when the thermo-responsive element 34 causes said movable contact 132 to move away from said selector contact 144 to break said primary circuit 48 and thus said power circuit 39 to stop said motor. It is thus obvious that I have provided an improved method and apparatus for regulating the air supply to the furnace through the medium of the flue gases to maintain a flue temperature indicative of the correct amount of oxygen for most efiicient combustion.

As stated hitherto, I provide in combina tion with said air controlmeans including an element in-theflue preferably. a thermo-responsive element acted upon by the flue gases to automatically control the air supply to said furnace means to automatically regulate the fuel supply to said furnace. In my preferred embodiment I employ a steam boiler furnace and the means to automatically regulate the fuel supply to maintain a constant boiler pressure is preferably controlled by the boiler pressure. The oil or pulverized coal in suspension is pumped'through the supply pipe 104 under pressure as usual and provide in said pipe 104, the diaphragm controller valve 180; Said valve includes the valve stem 182 normally'forced upwards by the spring 184 to keep the lower end 186 of the valve stem 182 out of the orifice 188 of a needle valve 187 in said pipe 104. The up r end 1900f said valve stem 182 is suita ly secured to the diaphragm 192. The chamber 194 in said valve 180 above said diaphragm 192 is connected by means of the pipe 196 to the boiler 22. It is thus obvious that when there is an increase in load and a correspond ing decrease in boiler pressure the spring 184 will force the valve stem 182 upwards to free the orifice 188 to permit an increase of supply of oil to said burner 24, but that on increase of pressure in said boiler 22 due to a decrease in load the diaphragm 192 will be forced downwards thereby forcing the valve stem 182 downwards against the tension of the spring 184 forcing the lower end 186 of said valve stem into said orifice 188 to lessen the fuel supply to said burner.-

As stated, my invention also comprises the method which consists of automatically regulating the fuel supply to a furnace and simultaneously automatically regulating the air supply to said furnace to secure the maximum CO content in the flue gases and the combination of means to produce said results. As hitherto stated my invention further comprises improvements in the' method of additionally automatically adjusting the air supply preferably through the medium of the fuel supply preferably by means of the boiler load to compensate for variations in the load and I provide in combination with the means hitherto described means to accomplish this additional function whereby the selected temperature may be automatically adjusted to compensate for variations in load on said boiler. In my preferred embodiments as shown in Figs. 1-10, I preferably accomplish this as follows. I provide means controlled by said valve 180 to move the automatic selector 138 of said contact formin device 130 to select the temperature most e cient for varying loads on said boiler. To accomplish this in my preferred embodiment,

I preferably provide the diaphragm valve with a depending bracket 204 provided with a transverse slot 206. I provide the lever 208 provided with a transverse slot 210 centrally thereof. I provide the bolt 212 to pivotally adjustably mount said lever 208 on said bracket 204. Phe power arm of said lever 208 comprises the end 214 retained in position between the collars 216 on said valve stem 182. The work arm 218 of said lever 208 is provided with the thumb screw 220. A bell crank lever 222 is suitably pivoted by the screw 224 on a bracket 226 attached to the furnace wall. The power arm 228 of said lever is adapted to be contacted by the thumb screw 220 on said lever 208 to move the work arm 230 thereof. A link 232 connects the work arm 230 of said bell crank lever 222 with said automatic selector 138. It is thus obvious that the pivot point of the lever 208 may be adjusted transversely of said bracket 204 by means of adjusting the pivot pin 212 therem to select the desired stroke of the automatic selector 138 to secure the correct range of temperature to agree with the range of variable boiler loads: In the preferred embodiment shown in Figs. 1-7, I provide the tension spring 234 to normally pull the automatic selector 138 through the medium of the link 232 to keep itin constant contact with its actuating mechanism. In the embodiment shown in Fi 8 I mount the thumb screw 220 on the wor arm 218 of the lever 208 so that it may directly abut a bolt 228 projecting upwardly from said block of the movable selector member 138. In this embodiment a spring 234 abuts the outer edge of the case 130' and a head 229 on the top of the bolt 228 to normally force the automatic selector 138 similarly upwards against the actuating mechanism. It is thus obvious that on increase of pressure in said boiler 22 due to a lesser degree of load that the arm 214 of the lever 208 will be forced down thereby permitting the spring 234 or 234' to move the automatic selector 1387towards-a lower temperature position and that on increase in load and corresponding decrease in pressure that the spring 184 will force the arm 214 of the lever 208 upwards thereby forcing the thumb screw 220 downwards against the member 228 to cause it to move the automatic selector 138 towards a, higher temperature and thereby increasing the selected temperature.

In addition, I provide auxiliary manually operated means for moving the automatic selector 138 to manually adjust the selected temperature. In either embodiment shown, said means comprises the thumb screw 240 or 240'- adapted to adjust the automatic selector 138 to secure the temperature desired. In the embodiment shown in Figs. 1-7, said thumb screw 240 functions against the power arm 228 of the lever 222 to force the automatic screws'220 may be screwed up out of the wa It is also obvious that either the manual y operated means for moving the automatic selector or the means controlled by the boiler load to automatically cooperate with the air control means to vary the air supply with Y changes in load'on said boiler may dispensed with.

In addition I provide independent manually operated means for regulating the louvre 26 and damper 32 to vary the air supply. In my preferred embodiment, said means comprises the clutch 99 separating the louvre drive shaft 97 into two portions whereby when the clutch 99 is disengaged the outer portion of said shaft which contains the worm 100 may be rotated by means of the hand. wheel 101 to independently regulate the louvre and damper particularly when startingup the furnace.

In Fig. 11 I have shown a modified form of my invention adapted for use on a domestic heating burner. In this embodiment the mo tive means comprises a hydraulic motor 36' actuated by a thermostat 34 identical in construction to. the thermostat used in the embodiment shown in Fig. 8. Said thermostat through the link mechanism 127 actuates the piston 250 having two heads 252 and 254 contained in and slidable in the piston valve 256. Said piston valve 256 is mounted on top of a cylinder 258 and connected thereto by the ports 260 and 262 on each side of the medial line thereof. A liquid discharge line 264 exhausts from the centre ortion of the piston valve 256. The liqui intake pipe 266 is split near the piston valve and enters in the up er cylinder near each end thereof through t e pipes 268 and 27 0 respectively. A piston 271 provided with the piston head 272 reciprocates in the cylinder 258. The piston 250 is connected to the slidable element 274 of a register 276 located near the base of the furnace, said register being connected to the damper 32' in the flue by means of the adjustable link mechanism 278. The operation of the means including an element in the flue acted upon by the flue gases to automatically control the air supply to said furnace is thus obvious from the above description. When the-selected temperature is attained it is obvious that the piston heads 252 and 254 will close the ports 260 and 262 so that there will be no movement of the piston 250. When however,,the piston 250 is moved in said piston valve 256 to move the piston head 254 to the left as shown in the drawing on in crease of heat in the flue it is obvious that water will flow through the inlet pipe 270 through the right hand side of the cylinder 258 to force the piston 271 to the left thereby closing the register 274 and damper 32', the liquid exhausting from the left hand side of the cylinder 258- through the now open port 262 across the piston valve 256 and out through the water dischar e line 264. It is obvious that on decrease 0 heat in said flue water will flow in through the inlet duct 268 to push thepiston 271 to' the right to open the register 2 4 and'the damper 32'. Though I have preferably shown the motive means 36' to move the register 274 and damper 32', it is obvious that where a particularly strong thermostat or other thermo-responsive device is employed that said motive means36' may be dispensed with.

0 provide means to automatically control the fuel supply to said furnace 1n com-f bination with said means heretofore described,though any suitable type of means for this purpose may be used, I preferably also employ a thermostat controlled by the room temperature-of one of the rooms desired to be heated. The oil inlet pipe 104 to said furnace is provided with a valve 280 having the actuating lever- 282 projecting therefrom. The weight 284 normally tends to pull down the lever 282 to open the pipe 104. The actuating lever 282 is controlled by the cord 285 moved up and down by the electric motor 286, said electric motor being controlled in its action by the thermostat 288 acting on the control electric circuit 290. The thermostat 288 as shown is of a well-known type comprising two members of two different coeflicients of expansion joined together into a spiral shape. pansions cause the spiral to open and close with changes in the room temperature, thereby striking the contacts 292 for closing the circuit for moving the motor 286 in either direction to open and close the valve 280 with changes in temperature. V

In Fig. 12 I have shown my invention adapted for use on an ordinary type of gasburning furnace. In this embodiment the means including the element in the flueacted upon by the flue gases for automatically controlling the air supply to said furnace comprise the thermostat 34 of a construction similar to that shown in Figs. 8-11 which through the medium of the link mechanism 127 opens or closes the valve 292 in the air supply pipe 294. The gas supply pipe 296 and air supply pipe 294 join in the mixing chamber 298 and are discharged therefrom at the burner head 28'. To provide means to automatically regulate the fuel supply to said furnace I provide an additional thermostat 300 in said gas line 296 preferably controlled The different relative exby the heat in the oven 302, said thermostat 300 operating to regulate the valve 304 located in said gas line 296. It is obvious that in all the embodiments shown in Figs. 8-12 the selected temperature may be regulated by means of turning the thumb screw 306 on the thermostat 32.

Though in all theembodiments shown I have shown the furnace equipped with one burner only, it is obvious that a plurality of burners may be employed in which the air for all the burners or the fuel for all the burners may each be controlled by a single unitary means.

As stated previously it is. obvious that any type of fuel, liquid, solid, such as pulverized coal or gaseous may be employed, though as explained, my invention is particularly of additionally regulating the fuel supply and also in combination therewith if desired the further step of automatically adjusting the air supply to compensate for variations in load on a boiler when employed and the improved apparatus hitherto shown and described for these purposes. As hitherto explained, my invention also includes the specific means I employ including an electric motor, an electric control through the medium of a primary circuit, a 3-phase circuit and solenoid switches, though it is obvious that if desired the relay switches may be dispensed with as well as the primary circuit and the power circuit may consist of a circuit of either single phase or direct current acting directly through whatever form of contact forming device may be employed. The motive means 36 may comprise one electric, hydraulic or other type of motor connected up so as to be reversible or may consist of two motors each to drive the louvre in opposite directions. As also explained, the louvre or equivalent device, such as the register 274 shown in Fig. 11 may be moved directly by the thermo responsive element without the necessity of interposing the drive and motive means.

It is understood that my invention is not limited to the specific apparatus shown or methods described and that various deviations may be made therefrom without departing from the spirit and scope of the appended claims.

- What I claim as new and desire to secure by Letters Patent is:

1. In a steam boiler furnace having a flue, the combination of means responsive to boiler load to automatically regulate the fuel supply to said furnace to maintain a substantiallycontrol the air supply to said furnace to deliver the correct amount of oxygen to said furnace to secure most. eflicientcombustion within the boiler rating, and means to adjust said air control means to vary the air supply in accordance with degree of overload on said boiler.

2. In a steam boiler furnace having a flue, the combination of means to automatically regulate the fuel supply to said furnace to maintain a substantially constant boiler pressure, an element in the flue acted upon by the flue gases, means controlled by said element alone to automatically control the air supply to said furnace to deliver the correct amount of oxygen to said furnace to secure most efficient combustion within the boiler rating, and means to adjust said air-control means to vary the air supply in accordance with degree of overload on said boiler.

3. In a steam boiler furnace having a flue, the combination of means responsive to boiler load to automatically regulate the fuel supply to said furnace to maintain a substantially constant boiler pressure, athermo-responsive element in the flue acted upon by the flue gases, and means controlled by said thermoresponsive element alone to automatically control the air supply to said furnace to deliver the correct amount of oxygen to said furnace to secure most eflicient combustion.

4. In a furnace having a flue, thecombination of means to automatically regulate the fuel supply to said furnace, a thermo-responsive element in the'flue acted upon by the flue gases and means controlled by said thermoresponsive element alone to automatically control the air supply to said furnace to deliver the correct amount of oxygen tosaid furnace to secure most eflicient combustion.

5. In a steam boiler furnace having a flue, the combination of means responsive to boiler load to automatically regulate the fuel supply to said furnace to maintain a substantialy constant boiler pressure, a thermo-responsive element in the flue acted upon by the flue gases, means controlled by said element alone to automatically control the air supply to said furnace to deliver the correct amount of oxygen to said furnace to keep said flue gases at a selected temperature for most efficient combustion 'within 'the boiler rating, and means responsive to variations in boiler load to automatically vary the selected temperatura in accordance with the degree of overloa 6. In a steam boiler furnace having a flue, the combination .of means to automatically regulate the fuel supply to said furnace to maintain a substantially constant boiler pres! sure, a thermo-responsive element in the flueacted upon by the flue gases means controlled by said element alone to automaticall control theair supply to said furnace to eliver the correct amount of oxygen to said furnace to keepsaid flue gases at a selected temperature for most efficient combustion within the boiler rating, and means responsive to variations in boiler load to automatically vary the selected temperature in accordance with the degree of overload.

7. In a steam boiler furnace having a flue, the combination of means responsive to boiler load to automatically regulate the fuel supply to said furnace to maintain a substantial- 1y constant boiler pressure, a 'thermo-r esponsive element in the flue acted upon by the flue gases and means controlled by said element alone to automatically control the air supply to said furnace to deliver the correct amount of oxygen to said furnace to keep said flue gases at a selected temperature for most eflicient combustion. v

I 8. In a furnace having a flue, the combination of means to automatically regulate the fuel supply to said furnace, a thermo-responsive element in the flue acted upon by'the flue gases and means controlled by said element alone to automatically control the air supply to said furnace tov deliver the correct amount of oxygen to said furnace to keep said flue gases at a selected temperature for most efficient combustion.

9. In a furnace having a flue, the combination of a therm'o-responsive element inthe flue and means connected thereto and automatically controlled by said elementalone to regulate the air supply to said furnace to maintainthe highest proportion of CO in the flue gases as indicated by a temperature previously determined by experimentation.

10. In a furnace having a flue, the com-1 bination" ofa thermo-responsive element in the flue and means connected thereto and automically controlled by said element alone to regulate the air supply to said furnace to maintain a temperature in said furnace previously determined by experimentation to indicate the highest proportion of CO in said flue. gases. Y I

11. The. method herein described which consists of automatically regulating the fuel supply to a steam boiler furnace in response to variations in boiler load to maintain a substantially constant boiler pressure, automatically' regulating the. air supply to said .furnace to secure themaximum CO5 content in the flue gases Within the'boiler'ratin and additionally automatically adjusting t e air supply through the medium of the boiler load to compensate for variations in degree of overload. j

12. The method herein described which consist of automaticallyregulating the fuelsupply to a steam boiler furnace, automatical 1y regulating the air su 1y to, said furnace to secure the maximum (i content in the flue ases within the boiler rating and additionaly automatically adjusting the air supply through the medium of the boiler load to concilpensate for variations in degree of overloa 13. The method herein described which consists of automatic-ally regulating the fuel supply to a steam boiler furnace in response to variations in boiler load to maintain a substantially constant pressure, automatically regulating the air supply to said furnace through the medium of the temperature of the flue gases alone to maintain a .selected temperature for most efficient combustion within the boiler rating and additionally automatically adjusting the selected temperature through the medium of the boiler load to compensate for variations in degree of over- 103d;

14. The method herein described which consists of automatically regulating the fuel supply to a steam boiler furnace, automatically regulating the air supply to said furnace through the medium of the temperature of the flue gases alone to maintain a selected temperature for most eflicient combustion within the boiler rating and additionally automatically adjusting the selected temperature through the medium of the boiler load to compensate for variations in degree of overload.

15. The method herein described which consists of automatically regulating the fuel supply to a steam boiler furnace in response to variations in boiler load to maintain a substantially constant pressure and automatically regulating the air supply to said furnace through the medimn of the temperature. of the flue gases alone to maintain a selected temperature for most efficient combusion..

16. The method herein described which consists of autoniaticall regulating the fuel supply to a furnace aml auton'iatically regulating the air supply to said furnacethrough the medium of the temperature of the flue gases alone to maintain a selected temperature for most efiicientcombustion.

17. The herein described method which consists in automatically regulating the air supply to a furnace through the medium of the temperature of the flue gases alone to maintain a fine tempe 'ature indicative of the correct amount of xygen for most efiicient combustion.

18. In combination. a furnace having a line for the products of combustion, a thermo-responsive element mounted in said flue, motive means. an adjustable air intake for said t'urnace, a reversible drive from said motive means to said air intake 0 )erative to regulate it and means controlled by said thermoresponsive element alone to actuate said motive means in either direction to adjust said air intake until a selected most efiicient temperature in the flue is attained.

19. In combination. a boiler, a furnace for said boiler having a flue for the products of combustion. a thermo-responsive element an electric circuit connected to said motive means, an adjustable air intake for saidburner, a reversible drive from said motive means to said air intake operative to regulate it, a contact forming device controlled by said thermo-responsive element and connected to said circuit, including a movable neutral contact member controlled in its position by said thermo-responsive element connected to the neutral wire of said circuit, and a movable selector member having two contactpoints insulated from each other, each separately connected to the circuit whereby on increase of heat in said flue said thermo-responsive element may cause said movable neutral contact member to contact one contact of said movable selector member to complete the circuit to drive said motive means in one direction to close said air intake to lessen the air supply until the temperature in the flue has been reduced to the selected temperature when the thermo-responsive element causes said movable neutral contact to move away from said selector contact to break said circuit, and vice versa to conjointly open said air intake on decrease of the heat in said fine until the temperature in the flue has been increased to the selected temperature.

20. Apparatus according to claim 18 in which the reversible drive from the motive means to the air intake contains a reducing train of gearing.

21. Apparatus according to claim 18 in which the reversible drive from the motive means to the air intake contains an intermittent gear to produce rest to compensate for lag and delay.

22. Apparatus according to claim 18 in which the flue is provided with a damper and the reversible drive adjusts the damper conjointly with the air intake.

23. Apparatus according to claim 18 pro-.

vided with means substantially responsive to variations in boiler load to automatically adjust the selected temperature in accordance with variations in load on the boiler.

:24. Apparatus according to claim 1 havipg means to automatically regulate the fuel supply to the furnace and means controlled by said means to adjust the selected temperature in accordance with variations in d on the boiler.

25. Apparatus according to claim lfihaving manually operated means for adjusting the selected temperature.

26. Apparatus according to claim 19 provided with means substantially responsive to variations in boiler load to automatically adjust the selected temperature in accordam'e with variations in load on the oiler and an auxiliary manually operated means for mannliil) out for re ating the air supply.

' 28. paratus according to claim 19 in which t e furnace burns oil, adiaphragm valve is connected tothe oil supply pipe and a pipe connects the boiler with said diaphragm valve, whereby the boiler pressure may regulate said valve to automatically supply the proper amount of oil to said burner to maintain a substantially constant boiler pressure and means controlled by said valve are provided to move the automatic selector of the contact forming device to select the templerature most eflicient for varying loads e boiler.

29. Apparatus according to claim 19 in which a power electric circuit actuates the motor and a separate primary circuit is provided and two solenoid relay switches are provided, each connected to the ower circuit and the primary circuit and eac alternately operative when closed by the primary circuit to close said power circuit to drive said motive means in opposite directions and each one alternately operative by the movable neutral contact member in the primary circuit contacting alternately opposite selector contacts.

30. A paratus according to claim 18 in which t e reversible drive from the motive means to the air intake contains means to produce rest to compensate for lag and delay.

' In testimony whereof I afiix m signature.

- JAMES A. ORAN.

ing independent manually operated means 

